基于固有频率变化率的桥梁支座病害识别技术的研究

发布时间：2018-05-04 14:38

本文选题：固有频率变化率 + 支座病害检测　；参考：《华东交通大学》2014年硕士论文

【摘要】：支座作为桥梁结构中重要的组成部分，它的造价虽然在桥梁建设费用中占得比例相对较低，但是支座在桥梁结构中起着重要的作用。它将上部结构的荷载传递到墩台上的同时，满足了桥梁上部结构在荷载、温度、混凝土收缩徐变等作用下的自由变形。由于各种原因，支座存在着各式各样的支座病害，直接影响桥梁的使用寿命和使用安全。现在桥梁支座的检测方法还比较原始，主要靠人工的尺量、观察进行，还停留在表观检测的阶段，对桥梁支座安装后的实际工作性能的检测研究还较少。由于支座的高度小、所处的部位光线较暗，而且支座的检测是高空作业，这给桥梁支座的检测带来了一定的困难，而桥台上的支座在胸墙的一面检测就更加的困难。现在支座检测的仪器还很简陋，仅靠肉眼观察、尺量的局限性很大，难以准确反映支座的实际工作状态，只有对支座作出定性、定量的分析，才能鉴定其使用情况[1]。基于桥梁振动理论的检测技术具有操作简便、效率高、经济成本较低、不需要阻断交通且不对结构造成损伤等优点，而且能够从全局对结构进行把握。桥梁支座作为连接桥梁梁体和桥墩的传力构件，在结构分析中作为桥梁的边界条件，对桥梁的振动特性的影响贡献较大。基于此本文分别以实验和数值计算的方法，讨论了运用频率变化率检测桥梁支座病害的方法。首先本文通过分析结构的运动方程，以及桥梁的结构体系，提出支座可以看成整个桥梁结构体系的一部分，它可以简化为连接桥墩与其桥梁的一根弹簧，支座对于结构的振动的贡献仅取决于支座的刚度，桥梁的各种病害对桥梁振动特性的影响是由于弹簧的刚度的变化造成的。其次，在理论分析的基础上本文以16米钢筋混凝土空心板式简支梁桥为基础，按1:5的比例，制作了三片钢筋混凝土试验梁，将支座的刚度变化转化为支座接触面积的变化。应用实验的方法，使用DHDAS5922振动采集系统，采用跳梁法采集了在支座正常布置情况下的自振频率以及在各支座刚度下降情况下自振频率，探索了桥梁支座刚度对桥梁的自振频率的影响。通过研究自振频率的变化率，得出桥梁支座刚度的变化对桥梁的自振频率变化率的影响趋势。通过实验发现：支座刚度的降低会影响结构的自振频率，且结构自身的固有频率会随着支座刚度的降低而降低。支座刚度变化对结构自振频率的影响随支座位置的不同而不同，靠近桥梁两侧的边梁支座对自振频率的影响要大于靠近桥梁中央的支座的影响。由多支座共同发生病害时，结构频率的总变化率高于单个支座分别发生病害时频率变化率的和，，由于各支座单独发生病害时频率变化率处于同一量级，所以随着病害支座数量的增加，结构的自振频率降低率呈阶梯变化。由此可以对病害支座的病害程度、病害位置、病害数量进行诊断。在实验得出结论后，应用midas FEA有限元软件按1:1的比例建立了两座桥的实体模型，应用特征值计算的方法，调整各支座到病害状态，对16米空心板式简支梁桥和一个主跨52米的预应力钢筋混凝土连续梁桥进行了模拟。将实验得出的结论推广到实际大小的桥梁模型中进行验证。通过本文的研究，认为可以应用测试桥梁自振频率的方法对病害支座的病害程度、位置、病害支座数量进行诊断。
[Abstract]:Bearing as an important part of the bridge structure, its cost is relatively low in the cost of the bridge construction, but the support plays an important role in the bridge structure. It transfers the load of the upper structure to the pier and the pier, and meets the effect of the load, temperature, shrinkage and creep of the upper structure of the bridge. For various reasons, there are a variety of support diseases for the bearing, which directly affect the service life and safety of the bridge. Now the detection method of bridge support is still relatively primitive, mainly by the artificial scale, observation, and the actual working performance after the installation of the bridge support. There are few tests. Because the height of the support is small, the light in the location is dark, and the inspection of the support is high altitude. This brings some difficulties to the detection of the bridge support, and the support on the abutment is more difficult to detect on the side of the wall. It is difficult to accurately reflect the actual working state of the support. It is necessary to make qualitative and quantitative analysis of the bearing so as to identify its usage [1].
The detection technology based on the bridge vibration theory has the advantages of simple operation, high efficiency, low economic cost, no need to block the traffic and not damage the structure, and can grasp the structure from the global. As the transmission part of the bridge beam and the pier, the bridge support is used as the boundary condition of the bridge in the structural analysis. The influence of the vibration characteristics of the bridge is greatly contributed. Based on this method, the method of detecting bridge bearing disease by frequency change rate is discussed respectively by the method of experimental and numerical calculation.
First of all, by analyzing the motion equation of the structure and the structural system of the bridge, it is proposed that the support can be considered as part of the whole bridge structure system. It can be simplified as a spring connecting the bridge pier and the bridge. The contribution of the support to the vibration of the structure depends only on the stiffness of the support and the vibration characteristics of the bridge's diseases to the bridge. The effect is due to the change of stiffness of the spring.
Secondly, on the basis of theoretical analysis, based on the 16 meter reinforced concrete hollow slab simple supported beam bridge, three steel reinforced concrete test beams are made according to the proportion of 1:5. The change of the stiffness change of the support is transformed into the change of the contact area of the bearing. The method of applying the experiment, using the DHDAS5922 vibration acquisition system, is used to collect the beam method. The influence of the stiffness of the bridge bearing on the vibration frequency of the bridge is explored through the study of the change rate of the vibration frequency of the bridge. The influence trend of the change of the stiffness of the bridge bearing stiffness on the frequency change rate of the bridge is obtained by the study of the change rate of the self vibration frequency. The reduction of the stiffness of the seat will affect the vibration frequency of the structure, and the inherent frequency of the structure will decrease with the decrease of the support stiffness. The influence of the change of the stiffness of the support on the vibration frequency of the structure varies with the position of the support, and the influence of the side beam bearing near the bridge is greater than that of the support near the bridge. The total change rate of the structural frequency is higher than that of the single bearing when the disease occurs, and the frequency change rate is at the same order of magnitude in the case of individual bearing diseases. Therefore, with the increase of the disease support, the reduction rate of the vibration frequency of the structure changes step by step. The disease degree, location and quantity of disease support were diagnosed.
After the conclusion of the experiment, the solid model of two bridges is established by using the Midas FEA finite element software according to the proportion of 1:1. The method of eigenvalue calculation is used to adjust the support to the disease state. The 16 meter hollow slab simple supported beam bridge and a prestressed concrete continuous beam bridge with a main span of 52 meters are simulated. The conclusion of the experiment is concluded. It is extended to actual size bridge models for verification.
Through the research in this paper, it is considered that the method of testing the natural frequencies of bridges can be used to diagnose the disease extent, location and number of disease supports.

【学位授予单位】：华东交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U445.7

【参考文献】